Multi-span optical fiber das system with amplified-filtered loopback (AFLB)

Patent metadata

Field	Value
Publication number	US-12571673-B2
Application number	US-202318224441-A
Country	US
Kind code	B2
Filing date	Jul 20, 2023
Priority date	Jul 21, 2022
Publication date	Mar 10, 2026
Grant date	Mar 10, 2026

Abstract

A sensing system may include a distributed acoustic sensing (DAS) station to launch a DAS signal as an outbound DAS signal, as well as a plurality of DAS loopback assemblies, arranged along a plurality of spans. The plurality of DAS loopback assemblies may be arranged to separately process the outbound DAS signal, and return to the DAS station, the outbound DAS signal, as a return DAS signal that comprises a backscattered Rayleigh signal. As such, a given DAS loopback assembly of the plurality of DAS loopback assemblies may include an Erbium-Doped Fiber Amplifier (EDFA) that is arranged to compensate the loss from Rayleigh scattering of the DAS signal, and a filter device having an optical filtering function that is arranged to selectively send back just a sensing wavelength of the DAS signal.

First claim

What is claimed is:

1 . A sensing system comprising:
a distributed acoustic sensing (DAS) station to launch a DAS signal as an outbound DAS signal; a plurality of DAS loopback assemblies, arranged along a plurality of spans, wherein the plurality of DAS loopback assemblies are arranged to separately process the outbound DAS signal, and return the outbound DAS signal to the DAS station as a return DAS signal that comprises a backscattered Rayleigh signal, wherein a given DAS loopback assembly of the plurality of DAS loopback assemblies comprises: an Erbium-Doped Fiber Amplifier (EDFA) that is arranged to compensate a loss from Rayleigh scattering of the DAS signal; and a filter device having an optical filtering function that is arranged to selectively send back just a sensing wavelength of the DAS signal.

2 . The sensing system of claim 1 , wherein the filter device comprises a DAS filter or an optical add drop multiplexer (OADM).

3 . The sensing system of claim 2 , wherein the filter device is an OADM,
wherein the DAS station comprises a plurality of light sources, arranged to launch the outbound DAS signal at a plurality of wavelengths, wherein a first OADM at the given DAS loopback assembly is arranged to add the Rayleigh backscatter signal as a first Rayleigh backscatter signal at a first wavelength of the plurality of wavelengths, and wherein a second loopback assembly of the plurality of DAS loopback assemblies comprises a second OADM that is arranged to add a second Rayleigh backscatter signal at a second wavelength of the plurality of wavelengths, different from the first wavelength.

4 . The sensing system of claim 3 , the DAS station further comprising a wavelength division multiplexer/demultiplexer, arranged to separate the first Rayleigh backscatter signal from the second Rayleigh backscatter signal.

5 . The sensing system of claim 1 , wherein the DAS station is located at a first end of an optical communications system, wherein the DAS station is configured to send the outbound DAS signal over a first link of the optical communications system, and wherein the plurality of DAS loopback assemblies are arranged to route the return DAS signal over a second link of the optical communications system.

6 . The sensing system of claim 5 , wherein the DAS station is a first DAS station, wherein the outbound DAS signal is a first outbound DAS signal, and wherein the return DAS signal is a first return DAS signal, the system further comprising:
a second DAS station, located at a second end of the optical communications system, wherein the second DAS station is configured to send a second outbound DAS signal over the second link of the optical communications system, and wherein the plurality of DAS loopback assemblies are arranged to route a second return DAS signal, derived from the second outbound DAS signal, over the first link of the optical communications system to the second DAS station.

7 . The sensing system of claim 1 , wherein a distance between adjacent DAS loopback assemblies of the plurality of DAS loopback assemblies, is between tens of kilometers to a few hundred kilometers.

8 . The sensing system of claim 1 , wherein the given DAS loopback assembly further comprises an optical switch to pass the return DAS signal to the DAS station when the optical switch is closed.

9 . The sensing system of claim 1 , wherein the DAS signal is launched over a plurality of N fiber pairs, wherein the plurality of spans comprises N spans, and wherein the DAS signal is routed through the given DAS loopback assembly over a dedicated fiber pair of the plurality of N fiber pairs.

10 . An optical communications system, comprising:
a distributed acoustic sensing (DAS) station to launch a DAS signal as an outbound DAS signal along a first path, and to receive a return DAS signal that is derived from the outbound DAS signal along a second path; a plurality of DAS loopback assemblies that are spaced from one another to define a plurality of spans, wherein the plurality of DAS loopback assemblies are arranged to separately process the outbound DAS signal, for return to the DAS station as a plurality of backscattered Rayleigh signals, respectively, wherein a given DAS loopback assembly of the plurality of DAS loopback assemblies comprises: an Erbium-Doped Fiber Amplifier (EDFA) that is arranged to compensate a loss from Rayleigh scattering of the DAS signal; and a filter device having an optical filtering function that is arranged to selectively send back just a sensing wavelength of the DAS signal.

11 . The optical communications system of claim 10 , wherein the DAS station is a first DAS station, wherein the outbound DAS signal is a first outbound DAS signal, and wherein the return DAS signal is a first return DAS signal, the optical communications system further comprising:
a second DAS station, located at a second end of the optical communications system, wherein the second DAS station is configured to send a second outbound DAS signal over the second path of the optical communications system, and wherein the plurality of DAS loopback assemblies are arranged to route a second return DAS signal, derived from the second outbound DAS signal, over the first path of the optical communications system to the second DAS station.

12 . The optical communications system of claim 10 , wherein the filter device comprises a DAS filter or an optical add drop multiplexer (OADM).

13 . The optical communications system of claim 12 ,
wherein the DAS station comprises a plurality of light sources, arranged to launch the outbound DAS signal at a plurality of wavelengths, wherein a first OADM at the given DAS loopback assembly is arranged to add a Rayleigh backscatter signal as a first Rayleigh backscatter signal at a first wavelength of the plurality of wavelengths, and wherein a second DAS loopback assembly of the plurality of DAS loopback assemblies comprises a second OADM that is arranged to add a second Rayleigh backscatter signal at a second wavelength of the plurality of wavelengths, different from the first wavelength.

14 . The optical communications system of claim 10 , wherein the DAS station is located at a first end of an optical communications system, wherein the DAS station is configured to send the outbound DAS signal over a first link of the optical communications system, and wherein the plurality of DAS loopback assemblies are arranged to route the return DAS signal over a second link of the optical communications system.

15 . The optical communications system of claim 10 , wherein a distance between adjacent DAS loopback assemblies of the plurality of DAS loopback assemblies, is between tens of kilometers to a few hundred kilometers.

16 . The optical communications system of claim 10 , wherein the given DAS loopback assembly further comprises an optical switch to pass the return DAS signal to the DAS station when the optical switch is closed.

17 . A method, comprising:
launching a DAS signal from a DAS station as an outbound DAS signal over a first path; processing the outbound DAS signal at a DAS loopback assembly of a plurality of DAS loopback assemblies; and returning to the DAS station a return DAS signal that is derived from the outbound DAS signal, after processing by the DAS loopback assembly, wherein the return DAS signal comprises a backscattered Rayleigh signal, wherein processing the outbound DAS signal of the DAS loopback assembly comprises: compensating a loss from Rayleigh scattering of the DAS signal using an Erbium-Do

Assignees

• Subcom Llc

Inventors

• Cai Jin-Xing
• Davidson Carl R
• Patterson William W
• Pilipetskii Alexei N

Classifications

• H04B10/25

  Arrangements specific to fibre transmission · CPC title

• H04B10/075

  using an in-service signal (H04B10/071 takes precedence) · CPC title

• G01H9/004 Primary

  using fibre optic sensors (light guides per se G02B6/00, acousto-optical devices specially adapted for gating or modulating in optical wave guides G02F1/125) · CPC title

• H04B10/0795 Primary

  Performance monitoring; Measurement of transmission parameters · CPC title